1. Field of the Invention
This invention relates generally to the casting of metals, and more particularly, to a horizontal continuous casting apparatus.
2. Description of the Prior Art
Continuous, horizontal casting of metals such as copper and its alloys typically requires a device which includes a casting trough and a holding furnace or the like having in one wall near the bottom a tapping hole which connects up to a nozzle through which the molten metal is transferred to the mold. For an example of one such system, reference may be had to published German Patent Specification DE-PS 26 57 207.
As will be readily appreciated by those skilled in the art, the components used for the melt transfer system in horizontal casting are generally made of refractory materials in some versions in combination with nozzles made of graphite or another suitable material, or of insulated or plasma coated metal. The outlet for the melt is situated near the floor of the holding furnace or casting trough and connects up with the opening in the lower part of the nozzle.
In U.S. Pat. No. 3,593,778, it is suggested that surface defects in the quality of the billet (such as scabbing and cracking) be often caused by the manner in which the melt is fed from the supply vessel to the mold. When casting round billets, for example, it is known to connect to the outlet opening a channel-shaped part having a refractory lining and configured as a disc defining a circular opening. The metal leaves the trough via the nozzle on its way to the mold, the nozzle opening forming an abrupt transition, as a result of its position with respect to the inner face of the mold. Billets produced from such a system are frequently subjected to surface flaws, such as, for example, differences in the quality of the upper and lower surfaces of the billet, opened or concealed shuts, laps, bleeding, roughness, and surface segregation. Inside the billet there can be clusters of particles, internal cracks, and dross. It therefore becomes difficult to guarantee uniform quality.
The arrangement of plates provided with openings for the passage of the melt directly prior to entering the mold should have a positive effect on billet quality. However, such an arrangement also leads to defects because billet shell formations are already effected on the mold side of the plates.
Defects similar to those noted above are also encountered when molds are fed from a pipe or nozzle having a diameter smaller than the cross section of the mold. However, if the cross section of the melt through-opening is identical to or greater than the cross section of the mold, the solidification of the billet (casting shell formation) is negatively influenced by the flow of metal brought about by the induction currents, particularly in supply vessels designed as inductively heated holding furnaces.
It is therefore an object of the present invention to provide a device which avoids these disadvantages and which ensures a uniform flow of metal, especially copper and its alloys, in the inlet region of the mold.